A Zero-Voltage, Zero-Current Transition Boost Cascaded-by-Buck PFC Converter for Universal E-Transportation Charging Applications

Two-switch converters (TSCs) are widely used and are more efficient at high-power levels with lower component stress than the single-switch topologies. These converters have flexible operations in both boost and buck modes and are applicable to on-board battery chargers in the power factor correction (PFC) converter stage. The intermediate output voltage at PFC can be greater or lesser than the peak of input voltage (variable dc-link voltage), resulting in higher switching losses across the boost switch. An auxiliary circuit proposed in this article comprises an active switch and a diode with a pair of resonant inductors and capacitors that are applied across the main switch to operate with loss-less switching. Though the conduction time of the proposed auxiliary circuit is small compared with the main converter operation but attains the main switch to turn-on with zero-voltage transition and turn-off with zero-current transition. In addition, the auxiliary switch involved in the converter operation is also subjected to SS. In addition, the proposed converter has no extra component stress and switching losses. With this, it can enhance the overall converter efficiency. The various operating modes involved in different time intervals are analyzed and presented in this article. Moreover, the design criteria of the auxiliary circuit and the main converter parameters are also discussed in this article. As a proof-of-concept, a hardware prototype of 1 kW is implemented with the proposed control structure, and the results are presented in this article. Maximum efficiency of 97.4% has been achieved from the implemented hardware prototype.